Structure and Function

Functions Support: body structure and shape Protection: vital organs surrounded Movement/Anchorage of Muscles Mineral Storage: calcium & phosphorus Blood Formation

Bone Composition Collagen: chief organic constituent (protein) Inorganic Calcium Salts: Vitamin D essential for absorption

Cells Osteoblasts: bone building, bone repairing cells in the periosteum Osteocytes: osteoblast embedded within the bone matrix Osteoclasts: cells that cause absorption of bone

Periosteum Dense, fibrous membrane covering bone Contains blood vessels Essential for bone cell survival and bone formation

Types of Bones Based on Composition Compact And Cancellous

Compact Bone Very Dense, Stress Bearing Haversian Systems Lamellae: concentric cylinder shaped calcified structure Lacunae: small lakes containing tissue fluid Osteocytes: facilitate exchange of calcium between blood and bone Canaliculi: canals connecting the lacunae together and to the haversian canal which carries nutrients/wastes

Cancellous Bone Light, Spongy Low Stress Areas Where Weight of Bone Would Be a Problem Found at Ends of Long Bones, Ribs, Sternum, Hips, Vertebrae, Cranium No Haversian Systems Web-Like Arrangement

Classification of Bones According to Shape Long Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones

Long Bones Extremities Femur, tibia, fibula, humerus, ulna, radius, clavicle Levers Epiphysis: at the ends; covered with hyaline cartilage for articulating bones; cancellous bone Diaphysis: shaft, covered with periosteum for bone growth, repair, nutrition; medullary canal with yellow and red marrow; endosteum lining; compact bone

Short Bones Cube-shaped Allows flexible movement Cancellous bone covered by compact bone Carpals, tarsals, metacarpals, metatarsals, phalanges

Flat Bones Flat Plates Protect Vital Organs Provide Broad Surface Area for Attachment of Muscles Cranial Bones, Facial Bones, Scapula, Sternum

Irregular Bones Peculiarly Shaped to Provide Support and Protection with Flexibility Vertebrae, Ribs, Ear, Hip, Hyoid

Sesamoid Bones Extra Bones Found in Certain Tendons i.e. Patella

Bone Formation Initially collagen fibers secreted by fibroblasts Cartilage deposited between the fibers Skeleton fully formed by 2 nd month of fetal development (all cartilage) Ossification begins after 8 th week of fetal development

Childhood and adolescence: ossification exceeds bone loss Early adulthood through middle age: ossification equals bone loss After age 35: bone loss exceeds ossification

Skull Bone Formation Begins as fibrous membrane Ossification center in the middle of the membrane Ossification begins in the middle and radiates out Ossification not complete at birth Fontanels (soft spots): molding of head during birth and allow for brain growth

Formation of Other Bones Begin as hyaline cartilage Short bones: one ossification center in middle and proceeds to periphery Long bones: three ossification centers (at each end and in the middle); ossification from each end toward the center and from the center towards each end

Bone Growth Grow in length at the epiphyseal line Grow in width by addition of bone to the surface Controlled by anterior pituitary (GH)

Bone Markings - Purpose Join one bone to another Provide a surface for attachment of muscles Create an opening for passage of blood vessels and nerves Use as landmarks

Bone Markings Process: bony prominence or projection Condyle: a rounded knuckle-like prominence usually at a point of articulation Epicondyle: small projection Head: rounded articulating process at the end of a bone Spine: a sharp, slender projection Tubercle: a small rounded process Tuberosity: a large rounded process

Trochanter: a large process for muscle attachment Fossa: a depression or a hollow Foramen: a hole Crest: a sharp ridge Line: a less prominent ridge of a bone than a crest Meatus: a tube-like passage Sinus/antrum: a cavity within a bone

Depression: a hollow-region or opening Fissure: narrow, slit-like opening Sulcus: a groove Facet: a small area on a bone

Bone Marrow - Yellow Medullary Cavity of Long Bones Fat Storage

Bone Marrow - Red Hematopoietic Tissue In cancellous bone in children In adults: cancellous bone of vertebrae, hips, sternum, ribs, cranial bones, proximal ends of femur and humerus Forms RBCs, platelets, some WBCs and destroys old RBCs and some foreign materials

Axial Skeleton Skull (22 Bones) Ear (12 Bones) & Hyoid Vertebral Column (26 Bones)

Skull - Cranium Houses and protects the brain Frontal: forms forehead and orbits of eyes Ethmoid: forms roof of nasal cavity Parietal: right & left; form sides and roof of skull Temporal: right & left; forms temple, cheek, ear openings

Occipital: back of skull; inferior portion has foramen magnum (opening for spinal cord) and 2 condyles to articulate with atlas Sphenoid: fills space between orbital plates; depression called sella turcica holds the pituitary gland; bat shaped

Cranial Sutures Unite the bones of the cranium As the child grow, irregular bands of connective tissue ossifies and turns into hard bone Abnormalities: microcephalus (premature fusion), hydrocephalus (delayed fusion  increases intracranial pressure)

Coronal Suture: between the frontal and parietal bones Sagittal Suture: between right and left parietal bones Lambdoidal Suture: between the parietal and occipital bones Squamous Suture: between temporal and parietal bones

Fontanels Fusion of the cranial bones is not complete at birth Space between the bones remains

Anterior (Bregmatic): “soft spot”, closes at 18 months Posterior (Occipital): triangular, closes at 2 – 3 months Anteriolateral (Sphenoidal): at 2 temples, closes at 2 – 3 months Posterolateral (Mastoidal): 2 behind ears, closes at 1 year

Facial Bones Guard and support eyes, ears, nose, mouth Nasal bones (2): form bridge of nose Vomer: forms central nasal septum Maxillary (2): upper jaw bone; fusion before birth; forms roof of mouth, walls of nose, floor of orbitals Mandible: lower jaw bone; largest bone of face

Zygoma (2): cheek bones Lacrimal (2): small bones form medial wall of each eye socket Palatine (2): forms back roof of mouth and floor of nose Inferior turbinate (2): forms curved ledge inside side wall of nose

Ear Bones Malleus (2): the hammer Incus (2): the anvil Stapes (2): the stirrup

Hyoid Bone U-shaped bone In neck At base of tongue Only bone in body that does NOT articulate with another bone

Cranial Sinuses Cavities within the cranium Resonance chambers for voice Decrease weight of skull Lined with mucous membrane

Frontal sinuses (2): above eyebrows, open into nasal cavity Ethmoid sinuses (2): between the eyes Spenoidal sinus (1): posterior to ethmoidal sinus, opens into nasopharynx Maxillary sinus (2): on either side of the nose, opens into the lateral wall of the nasal cavity

Vertebral Column

Functions Supports trunk and neck Protects spinal cord Multiple joint spaces allow for bending and twisting

Curves Allow for resilience and spring for walking Thoracic: present at birth Sacral: bow back Cervical: begins at 3 months when infant first begins to lift head Lumbar: begins when child first walks

Vertebrae 26 Separated by intervertebral disk to cushion joints for movement Body: thick, disk-shaped anterior portion Arch: encloses space for spinal cord; 3 processes for muscle attachment (spinous process – dorsally directed, 2 transverse processes)

Articular processes: provide for articulation with other vertebrae (2 superior and 2 inferior) Pedicles (2): originate from body of vertebrae notched to allow spinal cord nerves to pass Lamina: posterior wall of vertebrae, weakest point

Vertebral Sections Cervical - 7 bones Thoracic – 12 bones Lumbar – 5 bones Sacral – 5 fused bones Coccyx – 3 – 4 fused bones

Thorax 25 bones and cartilage Sternum, costal cartilage, ribs Walls covered by skin and muscles Floor formed by the diaphragm

Functions Protect and support heart and lungs Supports bones of pectoral girdle Plays leading role in respiration Ribs and sternum aid in RBC formation

Sternum Breast bone Sword and handle shaped Manubrium: handle, notched for 1 st 7 costal cartilages, articulates with acromium end of clavicle and 1 st rib Body: blade, notched for 1 st 7 costal cartilages Xiphoid process: tip, attachment site for diaphragm

Costal Cartilage Hyaline cartilage Connect ribs to sternum in 1 – 7 and to anterior ribs in

Ribs 12 pairs Attached posteriorly with vertebrae and anteriorly with costal cartilage True ribs: 1 st seven pairs of ribs False ribs: 8 – 12 (11 and 12 are floating)

Appendicular Skeleton – 126 Bones

Shoulder Girdle Clavicles (2): collar bones Scapulas (2): shoulder blades

Upper Extremities Humerus: upper arm Radius: thumb side of forearm Ulna: little finger side of forearm Carpals (8): wrist bones Metacarpals (5): hand bones Phalanges (14): finger bones

Pelvic Girdle Os Coxae (2): contains the acetabulum (hip socket) 3 components: ilium, ischium, pubis Also, contains the saccrum

Lower Extremities Femur: thigh bone Patella: kneecap Tibia: shin bone Fibula: lateral bone of lower leg Tarsals (7): ankle bones; talus and calcaneus Metatarsals (5): foot bones Phalanges (14): toe bones; great toe = halux

Articulations Synarthrotic: immovable Amophiarthrotic: limited movement i.e.pubic symphysis, vertebral joints, sacroiliac joint Diarthrotic: freely movable

The Framework